Chapter 15 - Insects And Fungi Attacking Ornamental Trees, Shrubs, Etc.,

Amount of injury done by insects
Remedies and preventives from injury by insects
Insecticides and their use
Fungi injurious to ornamentals
Rusts, smuts, mildews, blights, etc
Fungicides and their use
Spraying pumps and nozzles and their use.

One of the greatest difficulties one has to contend with in the care of ornamental trees, shrubs, etc., is the injury caused by insects and fungous pests, and in this chapter a brief outline of the most destructive pests will be given, with the best and most easily applied remedies.

The injury done to ornamentals by the above pests is very great, though not so large as that to fruit and garden crops. It is the history of all cultivated plants that the more largely any one kind is grown the more rapidly will its natural enemies, i.e., insects and parasitic fungi, increase, and the more ornamental homes we have the more need there will be to resort to protective or remedial measures to secure satisfactory growth.

No attempt will be made at a strictly technical description of species, but the author will endeavor to give a brief, plain description such as will enable the practical gardener or home-owner to detect the pests that may be injuring his pets and to apply remedies that shall save them from destruction.

In making up this list the author is indebted to the many carefully recorded results given in the bulletins of the experiment-stations published by   several States, which together with a large practical experience in the care of nearly all species and varieties of ornamental trees, shrubs, etc., he hopes will enable him to present the latest and best methods of preventing serious loss from the above pests. The reader is referred to the popular bulletins published by the various experiment-stations often giving illustrations of destructive insect or fungous pests with full treatment for their destruction. If one finds a pest at work and is not familiar with it, specimens should be sent at once to the entomologist or botanist of the station for Identification and advice as to remedies.

Insecticides. (Insect-destroyers.)

Practically there are but very few of the common insecticides needed or of much value in the preservation of farm, garden, or ornamental crops, and these are Paris green, arsenate of lead, hellebore, lime and sulphur wash and soluable oils, whale-oil soap, and pyrethrum-powder. The first, second, and third are used for the destruction of chewing insects and the others for sucking insects.

PARTS GREEN.—This is a chemical combination of arsenic or arsenious acid and copper, technically called arsenite of copper, which is used largely for making paint; the arsenic or arsenious acid being the element that kills insect life. It is a deadly poison and should be used with extreme caution and never be applied in large quantities to crops used as food or be kept in such places as to be accessible to irresponsible persons or children.

Pure Paris green contains but a small per cent of soluble arsenious acid and can be used upon most plants without injury in sufficient quantities to destroy any insects that feed by biting or chewing the parts. Samples containing more than four per cent of soluble arsenious acid should be used with considerable caution.

ARSENATE OF LEAD is similar in effect to Paris green, but is a combination of arsenic with lead instead of copper. It is less soluable than the former, adheres longer to the foliage and will not burn the leaves when used in large quantities. It can be used with the Bordeaux mixture and, being a white powder, may be more readily detected upon the leaves. In cost it is about the same in price per pound as Paris green, but about twice as much is needed to do effectual work. Arsenate of lead may be used as a dry powder with lime or flour or in water.

PARIS GREEK AND PLASTER, LIME, OR FLOUR.—In order to distribute Paris green more thoroughly and economically in a dry form it is often mixed at the rate of 1 lb. to 10 up to 50 lbs. of plaster or air-slaked lime or with from 10 to 20 lbs. of fine dry cheap flour. All of these substances possess some merit, but the two first are nearly as readily washed off by rains as the Paris green itself, while the latter when once moistened forms a paste that upon drying will remain on the foliage for a long time.

PARIS GREEN IN WATER.—By far the best method of applying this poison is mixed with water and applied with a nozzle that will make a very fine spray or mist. In this way it is more evenly distributed over the foliage or other parts, adheres better, and if lime is used in the water there will be much less danger from injury than if used in the dry form.

Paris green alone can be safely used only at the rate of 1 lb. to 250 or 300 gals, of water, This, however, is a very small quantity, and to enable more Paris green to be used lime is added to neutralize the soluble arsenious acid. Two lbs. of lime slaked in water and added to 25 gals, of water will enable us to use as much as 1 lb. of Paris green to 100 and even 50 gals, of water without injury to the foliage. When the Bordeaux mixture (see "Fungicides:') is used, the lime in that mixture has the same effect, and 1 lb. of Paris green to 50 or 100 gallons of the mixture may be used without injury to the foliage (except upon the peach and cherry trees), and the work of destroying insects and fungi thus reduced one half.

HELLEBORE-POWDER.—This is a fine powder made from grinding the roots of Veratrum album, and will kill most chewing insects. It, however, is more expensive and does not adhere so well to the foliage as Paris green, even if used in lime or water. It will not, however, injure the foliage, and is not nearly so poisonous—not dangerously so unless taken into the lungs or stomach in large quantities. It is best used in water or while the foliage is wet with rain or dew.

KEROSENE EMULSION.—Formula: ½ lb. common bar soap, 2 gallons water, 2 gallons common kerosene.

Dissolve the soap in the hot water; while still hot, add the kerosene and churn back and forth with a garden-pump or syringe until a soft soap or cream-like substance is formed. When cold, dilute with water to make from 10 to 25 gals, of liquid. This is used for the destruction of sucking insects like aphides (plant-lice), scale insects, etc.

WHALE-OIL SOAP is very frequently used as an insecticide at the rate of from 1 lb. to 3 to 5 gals, of water, according to the insect.

PYRETHRUM OR PERSIAN INSECT-POWDER.—This substance is made from the flowers of two or three species of pyrethrum or feverfew-plants, the flower-heads of which are ground to a fine powder, known in the markets as pyrethrum, Dalmatian, Persian, or Buhack insect-powder. When dusted upon some kinds of insects in the latter part of the afternoon or evening, it will paralyze them and those remaining under its influence during the entire night are killed. Many of these insects would soon recover if it were applied in the morning or middle of the day. Young insects are more susceptible to its effect than older ones, but as most of the aphides and other sucking insects are short-lived, several applications at intervals of a few days or a week will destroy most of them.

Fungi or Fungous Growths.

The use of fungicides becomes necessary to protect many of our trees and shrubs from fungous growths, i.e., mildews, rusts, blights, etc., which often do serious injury, and copper in one form or another is the substance most commonly used to destroy these pests. When once a fungous growth has become established in the tissues of a plant, nothing will kill or dislodge it that will not destroy the host plant, but the spores or seeds of the fungus may be killed or be prevented from germinating by a very small amount of copper solution coming in contact with them.

To prevent the growth, therefore, of the spores of rusts, smuts, mildews, etc., it becomes necessary to have the copper solution on the parts of the plants likely to be affected whenever the spores come in contact with the plant under conditions of high temperature and moisture. These spores are produced in immense numbers, an illustration of which may be seen in mass of spores forming the large fruit-bunches of the " corn-smut " or the dust of the puff-ball, the black substance of the first and the fine gray powder of the last being composed of myriads of spores or seeds. These spores are very small, so small in fact that they are individually scarcely perceptible to ordinary vision and are carried about by the slightest breath of air.

Much may be done to prevent the growth of fungous pests by keeping the trees or plants in a vigorous, healthy growth. This may be done by good cultivation and an abundance of plant-food, under which condition the growing spores are not so likely to gain a foothold in the tissues of the host plant; but even with the most vigorous growth we sometimes find that if the weather is unusually hot and the atmosphere very moist the spores will gain a foothold and we must have the copper solutions on the surface of the plant to prevent the growth of the spores should the plant not be able to withstand their attack.

Some seasons, and often for a series of years, our trees escape injury from fungous pests, but we cannot hope to escape always, and it is the part of wisdom to learn with what pests we are threatened, what is the best remedy, and how and when to apply such remedies as to most certainly destroy each pest.

Fungicides. (Fungus-destroyers.)

COPPER SULPHATE (Blue Vitriol).-—Copper has long been known to be destructive to the spores of nearly all kinds of moulds, mildews, rusts, etc., but not until within a few years has it been largely used for the purpose of destroying these growths on cultivated trees, plants, and farm crops. The form in which it is most used is that of copper sulphate or blue vitriol, in which the copper is united with sulphuric acid and is in the form of blue crystals. In this form it is very soluble and very injurious to the growing parts of plants unless used in a very dilute form; 1 part of copper sulphate to 1500 or 2000 parts of water being as concentrated as it can be used without injury. In this form it is quickly washed off by heavy rains and to prevent this lime is used with it, forming what is known as the

BOEDEAUX MIXTURE.—Formula: 4 lbs. copper sulphate, 4 lbs, caustic (unslaked) lime, and 50 gallons water.

By combining the copper and lime it is found that the copper sulphate may be used more freely and with less injury than if used alone, and that it will adhere a long time to the foliage. To make the Bordeaux mixture, dissolve the copper in hot water (or if placed in a coarse sack or basket and suspended in a tub of cold water it will dissolve in two or three hours, while if put in cold water on the bottom of a tub or vessel it remains un-dissolved for a long time). Then in a separate tub slake the lime thoroughly and when both are cold pour the two together, stirring constantly. Dilute with water to make 50 gals, of liquid. In this form it is more difficult to apply than a simple solution, but the lime causes it to adhere for a long time and spraying need not be so frequently done. Before using, the mixture should be strained through a burlap or fine wire strainer to take out the coarse particles of lime. The Vermorel or some other adjustable nozzle that will throw a very fine spray or mist must be used to distribute the material evenly and without waste over the surface of the plants.

If insects are found attacking the plants to be treated for fungous growths, Paris green may be added to the Bordeaux mixture at the rate of from 1 lb. to 100 or 200 gals, of the mixture, and, as stated on a previous page, the lime will prevent this large quantity of the Paris green from burning the foliage and two pests be destroyed at one spraying.

AMMONIACAL CARBONATE OF COPPER.—In conspicuous places the Bordeaux mixture is objectionable on account of the deposits of lime and copper that remain on the foliage, and therefore the above form of copper is used under such conditions. It is equally effectual with the Bordeaux mixture while it remains on the plant, but, being quickly soluble, is washed off with heavy rains and requires frequent renewals. It is also more expensive than the Bordeaux mixture.

Formula: 3 oz. copper carbonate, 3 qts. ammonia or sufficient to dissolve the copper, the quantity depending upon its strength. When used, dilute to make 25 gals, of liquid.

COPPER-SULPHATE SOLUTION.—A simple solution of copper sulphate, 4oz. to 50 gallons, is about equally effectual with the last and much less expensive. It must, however, be used after every rain.

Pumps, etc., for Applying Insecticides and Fungicides.

For the application of insecticides and fungicides there are a great many pumps, machines, and guns made for the purpose, and any of those made by reliable and long-established firms may be relied upon to do good work. In every ease it is desirable, if possible, to obtain a pump made as near home as possible, that parts may be replaced or repairs be made in case of breakage with as little delay as possible.

Nozzles.

The number of nozzles made for distributing insecticides and fungicides is almost as great as that of pumps, and there are many good ones. To do the best work the nozzle must discharge a fine mist-spray that will settle upon the foliage and other parts sprayed in very small particles and not run off. The one that gives the finest spray without clogging is the most satisfactory.

To carry the spray to the tops of trees of medium height the bamboo extension-rod or-½-inch brass pipe from 6 to 10 feet long can be used with success, but to carry it into very tall trees the hose must be carried up into the tree and the insecticides or fungicides distributed there from. With a large pump worked by two or three men or a small engine two or three streams may be thrown at once and the work be done rapidly and cheaply.

Some Common Insects Injurious to Ornamentals.

ELM-BEETLE (Galeruca xanthomelǽna),Fig. 154.—This in-sect (k), a beetle of yellowish-brown color, about ¼ inch long, somewhat resembling the striped cucumber-beetle, comes out from its hibernating-places in early summer and lays its eggs on the under side of the leaves as they unfold. These eggs are bottle-shaped, of orange color, are laid in clusters of from 5 to 20, and attached to the leaf by the larger end (e), The eggs soon hatch, and the larvǽ(g), of a slender form, about ½ inch long when fully grown, and yellowish-brown color with a yellow line or band along the back, feed rapidly and in from two to four weeks descend to the ground, where they pupate under some convenient shelter. In some sections of the country as many as three or four broods are produced in a season, but in northern New England it has not been proved that more than one brood matures.

Remedy.—This pest is destroyed by spraying with Paris green, 1 lb. to 200 gals, of water, or if 2 lbs. of caustic lime be slaked, strained, and pat into the water 2 lbs. of Paris green may be used with the same amount of water, i.e., 1 lb. to 100 gals, of water. The time for spraying is the last of May or early in June for the destruction of the beetles, and again about the middle of Jane for the larvǽ, and if all the larvae are not destroyed by the first spraying one or two more applications at intervals of a week or ten days must be made.

ELM-SCALE (Gossyparia ulmi), Fig. 155.—Very little seems to be known about the life-history of this insect, and yet it is one of the most widely distributed and injurious insects attacking the elm. It is a small, soft scale insect of a whitish color (f) that attacks both the American and European species of the elm. It is found on the under side of the branches, and when crushed leaves a stain on the fingers or clothing much like that of iron-rust. It injures the trees by sucking the juices of the young shoots and small branches. In many sections in Massachusetts they were so abundant during the season of 1895 that the leaves and bark of almost every tree were badly covered with a black substance resulting from the dust of the atmosphere adhering to the sticky exudations made by the insects deposited upon them, and from a black fungous growth similar to that found in the exudations of the pear-tree Psylla in our pear orchards. The leaves were also of a sickly yellow color and the trees made a very small growth.

Remedy.-—It has been found to be destroyed by the kerosene emulsion, applied thoroughly at the time when the. young are hatching out and moving from near the parent scale to other parts of the tree for permanent location, and again from five to ten days later. By close attention about June 1st the best time can be easily determined.

MAPLE-BORER {Plagionotus speciosus), Fig. 156.—In most sections where the sugar-maple thrives this insect is more or less injurious, though it is said to sometimes attack other species. It is a very dangerous insect enemy, because its work is difficult to detect until serious harm has been done. The perfect insect is a beetle nearly an inch long, the head is yellow, the thorax black, with transverse yellowish spots, and the wing-covers are yellow and black. The beetles appear in July and August, and lay their eggs on the bark during the latter part of the last-named month. The egg3 soon hatch and the larvǽ or young work a short distance under the surface of the bark, the first season throwing out chips and droppings from their holes. If not molested, the following season they go on feeding and working deeper through the bark and sapwood, making a tortuous burrow not far from the surface, often nearly £ of an inch in diameter and sometimes girdling the tree. As many as twenty have been found in a single tree.

Remedy.—The only effectual remedy is to dig the borers out before they have done much harm, i.e., the first fall or following spring after the eggs are laid. This may be very easily done with little or no injury to the tree. The bark should be carefully scraped and after a few days the surface carefully examined, when the exuded dust or chips will enable one to quickly detect the location of the borer. If the insects have already done serious harm to the tree, all holes or channels made by them should be filled up with putty, grafting-wax, or a thick paint. Possibly the painting of the trunk with lime or Portland-cement wash containing Paris green at the rate of 4 oz. to the gallon may prove effectual in destroying many of the larvǽ as they work their way into the tree.

CANKER-WORMS (Anisopteryx pometaria and Palǽcrita vernata), Figs. 157 and 158.—These insects extend over a wide area of the country, and are very injurious to the elm, apple, and some other trees. The male (a) insect is a grayish moth of about ½ inch stretch of wings and flies in the night, while the female (b) has no wings. The female crawls up the tree and lays its eggs in clusters on the branches during the night at any time from October 15th to April 15th when the ground is not frozen and in warm, moist nights. The eggs hatch out about the time the buds unfold, and unless destroyed the larvae soon eat all of the leaves but the skeleton and midrib, giving the trees the appearance of a fire having burned off the foliage.

FIG. 156—Maple-Borer. (Saunders : 5th Report U. S. Ent. Com., p. 375, Fig. 137.)

Remedy.-—The remedy so generally used of putting bands of tar or printer's ink, or of tin or other kind of troughs with oil in them, around the trees to prevent the female insects from reaching the branches is effectual provided the band is kept covered with soft ink or tar or the trough is well filled with oil when the insects are moving, i.e., at any time when there is no frost in the ground, on warm nights from November 15th to April l5th. The more satisfactory remedy, except for very tall trees, however, is to give the insects no attention until the eggs begin to hatch out, and then to destroy the larvae by spraying with Paris green used as for the elm-beetle, "making two applications, one when the first eggs hatch and then again in from five to eight days, according to the weather, or when all of the eggs are hatched out. Success in this work depends upon how much Paris green is used and how thoroughly the foliage is covered with it. For the amount of Paris green to use and method of application see " Treatment of the Elm-beetle," pages 269 and 270.

BORERS.—The maple-borer, Fig. 156, has already been described, but there are many ornamental trees besides the lindens, poplars, locusts, and many other trees are also injured by borers. These are to be destroyed in the same manner as the maple-borers, i.e., by digging them out, carefully examining all trees twice each season—in June and August.
 
HEADED APPLE-BOREB (Saperda Candida), Fig. 159, and the FLAT-HEADED BORER (Ghrysobolhfis femorata), Fig. 160;

  FIG.  16—Peach-Borer.
(Marlott; Circular No. 17, 2d Series, Dept. Apr., Fig. 1.)

ROSE-BUG OE CHAFER  {Macrodactylus subspinosus), Fig. 162.—This insect needs no description, and no one insect is more injurious to so many kinds of trees and shrubs and none more difficult to destroy or prevent from doing much harm.

        FIG. 162—Rose-Hug Or -Chafer. (Riley : " Insect Life," Vol. II., p. 295, Fig. 61.)

Remedy.—Where Paris green can be safely used, as it can be upon all trees and plants producing flowers that are not cut for house or personal decoration or that produce no edible fruit, this is the most certain remedy. On roses it can be used until the blossoms are nearly open and longer if the flowers are allowed to remain on the bushes until the petals fall. Pyrethrum-powder dusted over the bushes each forenoon and again in the afternoon in bright weather will drive the beetles away, but they soon return and the remedy must be repeated each day until they are done working. If this powder has been kept over one season or a considerable time in an open package, it loses its strength. It should always be kept in a sealed can or glass-stoppered bottle, and a fresh supply be obtained each season. Where rose-bushes are but few, these insects can be kept from doing serious injury by hand-picking; the easiest way to gather them being to take a broad, shallow tin basin, put in a little water with a tablespoonful of kerosene on top8 hold the basin under the part of the bush examined, and touching the insects they will fall into the pan and be destroyed.

ROSE-SLUG (Monostegia rosea), Fig. 163.—The rose-slug is the larva of one of the saw-flies. The perfect insect comes out of the ground the last of May or early in June. The eggs are laid under the epidermis or skin of the leaf, and the larvae appear in about two weeks, feeding upon the soft green parts of the leaf and leaving nothing but the midrib, veins, and epidermis on one surface. It is of a greenish color, nearly transparent, the head much larger than the posterior part of the body. It feeds rapidly and must be attended to soon after the eggs hatch.

FIG. 161—Rose-Hug Or -Chafer. (Riley : " Insect Life," Vol. II., p. 295, Fig. 61.)

FIG. 162—Rose-Hug Or Chafer

FIG. 163—Rose-Si.Ug.  (Riley : " Insect Life," Vol. V., p. 874, Fig-. 37.)

Remedy.—Dusting or spraying with hellebore or pyre-thrum-powder is a certain remedy.  If the dry powder is used, it must be applied when the foliage is wet with rain or dew. When used in water, 1 tablespoonful to a common 2-gal. pail of water is about the right quantity.

ROSE-LEAF HOPPER (Typhlocyba rosea).—This insect is small, almost white in color, and flies or jumps about whenever the trees or bushes are suddenly jarred. It feeds upon the green coloring-matter of the leaf, sucking out the juices, making very numerous small white spots until the leaf becomes very light green or almost white. It is especially injurious to the rose, grape-vine, etc., though it attacks some other shrubs and trees.

Remedy.—The remedy is thorough spraying with kerosene emulsion, or by the use of pyrethrum applied just at night it may be kept under control.

RED SPIDER (Tetranicus telarius).—This insect is so minute as to be difficult to detect with the naked eye except by the closest inspection until it has done considerable mischief, when its work is shown in the light green or grayish color of the leaves attacked. It works only in very dry and hot weather, when it increases very rapidly and attacks a great many kinds of trees and shrubs under the above conditions.

Remedy.—As this insect cannot exist in a moist, cool atmosphere, the spraying of the trees with cold water applied with considerable force is a certain remedy, a heavy thunder-shower often completely checking their work. Dusting the foliage with flowers of sulphur when the leaves are wet will also have a beneficial effect.

APHIDES {Aphis sp.).—There is hardly a species of tree or shrub that is not more or less affected by aphides (or plant-lice so called), yet but few of them are seriously injured. One season they are abundant and do much harm, and another very few and do little injury. These insects increase with astonishing rapidity; a single pair, it is said, ' may be responsible under favorable conditions of food and temperature for more than 1,000,000,000 progeny in a single season. They injure plant-tissues by sucking the juices of the tender parts, and when numerous all of the terminal shoots are stopped in growth and the tree or plant has a stunted, sickly appearance. When the leaves alone are attacked, they curl and roll up, and are soon covered with black substances collected from the dust of the atmosphere coming in contact with the sticky surface caused by the exudations of the aphides.

Remedy.—The application of kerosene emulsion with force enough to drive it under the curled leaf is the most satisfactory remedy. If very abundant, the 10-gal. formula should be used. On small trees and shrubs, where the branches can be bent down, dipping the ends into the emulsion would be most satisfactory, or the strong solution may be applied with a soft paint-brush.

SCALE INSECTS.—Scale insects are among the most destructive of the sucking kinds, and several species are very abundant. Among those most to be feared are the OYSTER-SIIELL SCALE and the SAN JOSE SCALE. The former (Mytelaspis pomorum), Pig. 164, is very common on ash, willows, lilacs, hawthorn, and on the flowering apples. In shape it resembles the oyster-shell, is of a brown color, about -g of an inch long by 1/16 wide, and injures the tree by sacking the juices from the growing shoots and brandies. At c it is shown natural size. The eggs hatch out from under the parent shell the last of June or early July, and the young swarm out and soon fix themselves on other branches, feeding at this point until they reach full size, when they die, leaving the young or eggs protected by their dead bodies.

FIG. 164—Oyster-Shell Scale. (Howard : '-Year Book," Dept. Agr., 1894, p. 257, Fig, 26.)

Remedy.—This pest may be destroyed by painting during the winter with a very light coat of linseed-oil, by washing with strong caustic potash, 1 lb. to 2 qts. water, by strong whale-oil soap, 2 lbs. to 1 gal. of water, applied while the trees are dormant, or by kerosene emulsion used just after the young insects have left the cover of the parent scale and have a very delicate covering.

The SAN JOSE SCALE (Aspridiotus perniciosus), Fig. 165, so destructive to all kinds of fruit and manv ornamental trees in California and the South, has been largely distributed about the country, having been found in every State in the Union, and is sure to prove a destructive pest unless destroyed as soon as discovered. The perfect insect is circular in outline, of a gray color, varying from 1/60 to 1/16 of an inch in diameter, and generally with a black spot in the centre. It is so small as to escape notice until it has increased to great numbers, and it propagates very rapidly. It injures plant-growth in the same way as the last by sucking the juices of the tender parts. There are many species of scale insects so closely resembling this pest that when insects of this kind are found they should be sent to the experiment station entomologists for identification and suggestions as to remedies.

FIG. 165—San Jose Scale.
(Howard : " Insect Life," Vol. VII., p. 835, Fig. 33.)

Remedy.—This pest has been destroyed in some cases by the same, but more concentrated, remedies as used for the oyster-shell scale. The applications should be made more thoroughly and more frequent use of the kerosene emulsion during the summer. If promptly attacked when first discovered it may be kept under control at a small expense. The most effectual remedy is the lime and sulphur or lime salt and sulphur solution applied just before the buds have started in the spring. The formulas and full directions for these applications may be found in the reports of the experiment stations, or upon application to the entomologists of these institutions.

MAPLE WOOLLY SCALE (Pseudococcus aceris), Fig. 166. —This comparatively new insect pest has appeared in several sections of the country, but thus far has been found only on the soft maples. In Europe it is reported to be injurious to the linden, elm, chestnut, etc. (see " Bulletin N. H. Ex. Station, No. 36 "), and should it increase in this country will prove a very troublesome pest. It is somewhat of the nature of the scale and aphis, sucking the juices of the plant upon which it feeds; its body and the masses of eggs which it lays being covered with a white cottony or woolly substance, from which it takes its name.

Remedy.— While no experiments have been made, or at least reported, to prove the value of the various common insecticides in destroying this pest, from the nature of the insect it seems probable that the kerosene emulsion will be effectual if applied with considerable force so as to throw it in under the mass of insects and eggs which are so nicely protected by the woolly cover that is of a somewhat oily nature, thus preventing watery liquids from adhering or penetrating to the bodies of the insects or masses of eggs.

FIG. 166—Maple-Scai,E.
(Howard : Circular, No. 3, Dept. Agr., 2d Series, Fig. 1.)

There are a great many other less injurious insects that often appear in small numbers on single trees or within limited localities, sometimes increasing rapidly for a time and then disappearing; but the limits of this volume will not allow of further space for their description. We may briefly say that in a general way the remedies already described may be applied to all insect pests, i.e., all chewing insects to be destroyed by the use of Paris green and all sucking insects by the kerosene emulsion.

Whenever a new insect appears, if doing harm to any crops, specimens should be sent to the entomologist of the experiment-station of the State in which it is found, and the instruction given for its destruction be followed. These stations are established for the purpose of aiding the people to overcome all difficulties in the growth of ornamental or useful crops, and every citizen should be free to ask for instruction and aid whenever needed.

Fungi Injurious to Ornamental Trees, Shrubs, etc.

The fungous growths that are injurious to growing plants belong to the group of plants known as parasitic fungi and take their food from their host plant, i.e., the plant upon which they grow, but organize no plant-food for themselves, and often they feed and grow with such rapidity as in a short time to destroy the host plant or seriously weaken it. Most of these parasites propagate from very minute seed-like bodies already described. They grow under favorable conditions with the most incredible rapidity, as may be illustrated by the short time in which the leaves of a pear or poplar tree are destroyed by the pear-blight or the poplar-rust. It often takes but a few days of warm, moist weather to cause the destruction of all of the leaves of many trees, when perhaps the growth of but a few spores only began the work of destruction. It is during hot, moist weather that they grow most rapidly, and while we may sometimes escape if we do not use fungicides, the wise gardener will be prepared to make the application of the fungicides described on previous pages.

Among the many fungi injurious to ornamental trees, shrubs, etc., the following are among the most destructive:

RUSTS.—This term has been applied in more or less of an arbitrary manner to a large group of fungi that produce masses of spores on the surface of the leaves, generally yellowish or brownish in color, but when of a white color they are often called the " white rusts " or mildews. The spores germinate on the surface of the leaves, their roots or feeding-parts (called mycelia) penetrate the leaf through the stoma or breathing-pores, and after feeding and developing for greater or less time, according to the species or the condition of the weather, fruit (spores) is produced on stalks or in masses on the surface of the leaf, these spores being scattered by the slightest breath of air. Of the true rusts I shall mention only a few of the most important, with the remedies most effective, but many others of a similar character may be destroyed or prevented from doing harm in the same manner.

POPLAR-RUST (Melanosporium populina), ROSE-RUST (Phragmidium mucronatum), HOLLYHOCK-RUST (Puccinia malvacearum), LINDEN-HUST {Cercospora microsora).— The growth of all of these pests takes place under about the same conditions, i.e., a weakened growth of the tree or plant from any cause and in close, moist, hot weather. Strong-growing, healthy plants are less liable to attack than those of a weak growth, though a too vigorous and soft growth  may  be  produced  by too  much  enrichment of the soil, which is as much to be avoided as the other extreme.

Remedy.—If copper in even minute quantities is on the leaves and branches so that it will be distributed over the surface whenever it rains or is wet with dew the spores cannot germinate, and the remedy to apply is to spray the branches thoroughly with copper sulphate, 1 lb. to 25 gals., or strong Bordeaux mixture, before the leaves unfold, when all of the earlier spores upon them will be destroyed. Then if the trees are where the latter mixture will not be too conspicuous that may be applied at intervals of from two to four weeks through July and August. If the trees are in a very conspicuous place, the dilute copper sulphate, 1 lb. to 250 to 300 gals., may be used, or the ammoniacal carbonate of copper will be equally effectual if applied more frequently—as often as every two weeks and after heavy rains. The great advantage of the Bordeaux mixture is that it holds the copper firmly to the leaves and with every rain or heavy dew minute quantities are dissolved and the spores are prevented from germinating.

LEAF-BLIGHTS.—The leaf-blights are unlike the rusts in that they attack and destroy small portions of the leaves, and when these spots or places of attack become nnmerous the whole leaf is destroyed and it soon falls off. Among the most destructive of the leaf-blights are the CATALPA-LEAF SPOT (Phyllosticta catalpǽ), CHERRY- AND PLUM-LEAF BLIGHT (Cylindrosporium Padi), MAPLE-LEAF SPOT {Phyllosticta acericolor), SYCAMORE-LEAF BLIGHT (Glmo-sporium nervisequum), ROSE-LEAF SPOT (Actinonema rosǽ), etc.

Remedy.—As with the rusts, the copper must be on the plants to destroy the spores when they come in contact with it, but when the parasite has become fully established nothing will destroy it that will not destroy the host plant. The treatment is the same as for the rusts.

MILDEWS OK WHITE BUSTS.—As the name indicates, these are parasites which produce white spores and more or less white patches on the leaf or other parts. As with the two previously named groups, they grow under conditions of moisture and hot, moist weather, and as a rule they appear later in the season.

Among the most destructive of this group are the ROSE-MILDEW (Sphǽrotheca pannosa), POWDERY MILDEW OF THE HAWTHORN", PLUM, AND CHERRY (Podosphǽra oxy-canthǽ), DOWNY MILDEW OF THE WILLOW (Uncinula salicis), DOWNY MILDEW OF THE LILAC (Microsphǽra Aim D. C.) etc.

Remedy.—Coming on later in the season than the brown rusts, two or three applications of either the Bordeaux mixture, dilute copper sulphate, or the ammoniacal carbonate of copper will be effectual, but no application need be made generally until the middle or last of July.

Flowers of sulphur if dusted over trees and shrubs will often reduce the mildews, but not often wholly destroy them.

As with new insects, fungi new to any individual that may appear to be doing serious harm may be sent to the experiment stations for identification or for suggestions as to the best remedies.

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